Mobile devices are particularly vulnerable to theft. Mobile device users usually carry their devices wherever they go. They often carry and use their devices in public places, such as in school, in stores and restaurants, or on airplanes. In these situations, their devices may be easily lost or stolen. Also, another person may be able to gain unauthorized access to a user's mobile device for a period of time while the user is otherwise occupied.
A person who has stolen or otherwise has unauthorized access to a user's mobile device may attempt to access data stored on the device by entering a device password. A typical mobile device, such as a smartphone is protected with a four-digit or six-digit password. The person may attempt to use brute force to gain access by repeatedly entering a different password until access is obtained. The longer the time the person has to attempt brute force access, the greater the chances of the person obtaining access. For example, a four-digit password only requires a maximum of 10000 tries to get access (average of 5000 tries). In certain situations, this may be relatively easy to accomplish. It may be even easier if the intruder has knowledge or semi-knowledge of the password.
Additionally, in some mobile devices entry of an incorrect password a certain number of times may lock the device or erase the contents of the device. In situations where another person has unauthorized access to a mobile device for a period of time and could try to unlock the mobile device while the user is otherwise occupied, this could cause loss of use or loss of data for the owner of the mobile device.